From b2cc4449430eba1840dde2c85d192b7305f11074 Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Sat, 14 Apr 2018 14:43:21 +0200
Subject: [PATCH] OVR: Add option to reset observer position

---
 src/libovr/ovr.c     | 21 +++++++++++++++++++++
 src/libovr/ovr.h     |  1 +
 src/mercenary/main.c | 11 +++++++++++
 3 files changed, 33 insertions(+)

diff --git a/src/libovr/ovr.c b/src/libovr/ovr.c
index 79fd874..62c2a03 100755
--- a/src/libovr/ovr.c
+++ b/src/libovr/ovr.c
@@ -99,6 +99,12 @@ static ovrEyeRenderDesc eyeRenderDesc[2];
 static ovrPosef hmdToEyeViewPose[2];
 static ovrLayerEyeFov layer;
 static long long frameIndex = 0;
+static double observer_x = 0.0;
+static double observer_x_normalize = 0.0;
+static double observer_y = 0.0;
+static double observer_y_normalize = 0.0;
+static double observer_z = 0.0;
+static double observer_z_normalize = 0.0;
 
 int init_ovr(void)
 {
@@ -240,6 +246,14 @@ void begin_render_ovr_eye(int eye)
 	y = layer.RenderPose[eye].Position.y;
 	z = layer.RenderPose[eye].Position.z;
 
+	/* normalize height to game's observer, if requrested by user */
+	observer_x = x;
+	x += observer_x_normalize;
+	observer_y = y;
+	y += observer_y_normalize;
+	observer_z = z;
+	z += observer_z_normalize;
+
 	glRotatef(-roll / M_PI * 180.0,0,0,1);
 	glRotatef(-pitch / M_PI * 180.0,1,0,0);
 	glRotatef(-yaw / M_PI * 180.0,0,1,0);
@@ -314,6 +328,13 @@ void render_mirror_ovr(int view_width, int view_height)
 	glDisable(GL_TEXTURE_2D);
 }
 
+void normalize_observer_ovr(void)
+{
+	observer_x_normalize = -observer_x;
+	observer_y_normalize = -observer_y;
+	observer_z_normalize = -observer_z;
+}
+
 void exit_ovr(void)
 {
 	int eye;
diff --git a/src/libovr/ovr.h b/src/libovr/ovr.h
index 68aa6d5..4b8b8ee 100755
--- a/src/libovr/ovr.h
+++ b/src/libovr/ovr.h
@@ -6,4 +6,5 @@ void begin_render_ovr_eye(int eye);
 void end_render_ovr_eye(int eye);
 void end_render_ovr(void);
 void render_mirror_ovr(int view_width, int view_height);
+void normalize_observer_ovr(void);
 
diff --git a/src/mercenary/main.c b/src/mercenary/main.c
index c94708b..8be3591 100644
--- a/src/mercenary/main.c
+++ b/src/mercenary/main.c
@@ -725,6 +725,14 @@ static void keyboard_sdl(int down, enum keycode keycode)
 			if (config_ctrl_c)
 				quit = 1;
 			break;
+		case KEYCODE_n:
+#ifdef HAVE_OVR
+			normalize_observer_ovr();
+			osd_info("", "change height");
+#else
+			osd_info("", "not applicable");
+#endif
+			break;
 		case KEYCODE_KP_PLUS:
 			if (config_fov / 1.2 >= FOV_MIN)
 				config_fov /= 1.2;
@@ -1026,6 +1034,9 @@ int main(int argc, char *argv[])
 		"        Press `CTRL' + `A' to toggle audio filter on / off.\n"
 		"        Press `CTRL' + `+' or `-' to change field-of-view (OpenGL).\n"
 		"        Press `CTRL' + `I' to skip intro (approaching to Eris).\n"
+#ifdef HAVE_OVR
+		"        Press `CTRL' + `N' to normalize player position.\n"
+#endif
 		"\n"
 		"Answer to a Question:\n"
 		"        Press `O' (not Zero) for OK and other key for NO.\n"
-- 
2.13.6